Our aim is to understand the mechanism in the behavior of a relatively simple organism by genetic dissection. This is done by producing lesions with mutagenesis and analysing the resultant effects on behavior, electrophysiology, ultrastructure, and the biochemistry of the system. The organism of choice is Paramecium aurelia. Using locomotion as the indicator of the state of the excitable membrane, mutants with defective ion "channels" or "gates" have been isolated and analyzed. We intend to continue this interdisciplinary research. Specifically, we propose to screen for other mutants with membrane defects which are over-sensitive or resistant to higher concentrations of K ion or Ba ions. Mutants so obtained and those on hand will be studied genetically and electrophysiologically with standard breeding analyses and intracellular recordings. Replicas of freeze-fractured surface membranes at resting or excited states will be examined. The purpose of this is to look for a structural basis of excitation, e.g. a voltage-induced 2-D protein polymerization on the lipid bilayer that forms the ion channels. Excitation related K efflux will be studied by flame photometry. 133Ba and possibly 22Na fluxes will be analyzed to improve on the existing 45Ca flux assay of excitation. Ba and Ca deposits in wild type and mutants will be examined. The fate of these ions that have entered during excitation may tell us how ciliary reversal occurs. Two-dimensional gel electrophoresis of the ciliary membrane proteins will be continued. Photoaffinity labelling of the K ion channel will be tried. We will also compare the ciliary Ca-ATPase activity of wild type and the "paranoiac", since the mutant shows suggestive ultrastructural changes.